THE toll of “pizzo” protection payments made by firms to Sicily’s Mafia is closely monitored. Nearly half pay up these days, according to estimates from the Confartigianato, a national business association—a big improvement from the early 1990s, when at least four-fifths of Sicilian firms paid it. Back then the levy claimed nearly a tenth of the turnover of victimised businesses. Today’s ratio is around half that. Other regions in Italy’s south, where the pizzo system is most entrenched, have also seen big drops.

For that businesses can thank a clutch of anti-pizzo groups. One is Addiopizzo (“goodbye, pizzo”) in Palermo, which advises businesses on pressing charges against crooks. It also encourages them to publicly forswear pizzo payments. Extortionists now think twice before bullying shopkeepers, knowing there will be a flurry of media...